PLATE 12 
Spongospora subterranea and Phoma tuberosa: 
Fig. A.—Section of a potato tuber through a sorus around which no dryrot has 
as yet set in. Spore balls are numerous and cork cells absent at the base of the 
sorus. Xno. 
Fig. B.—Section of a potato tuber made through a sorus of Spongospora subterranea 
after the tuber had been held in storage and some dryrot due to desiccation had devel¬ 
oped. A tendency toward the laying down of cork at the base is shown, but the 
cork cells have not yet thickened. X i io. 
Fig. C, D.—Two views of the pycnidia of Phoma tuberosa as grown in pure culture. 
Figure C shows the pycnospores emerging from the ill-defined ostiole. X650. 
Fig. E.—Pycnospores. X2,6oo. 
Fig. F.—Mature “bulbils” of Papulosporacoprophila (Zukal) Hotson, which in the 
tissues of potato tubers may be mistaken for spore balls of Spongospora subterranea . 
X650. 
Fig. G.—Spores of fungi associated with Spongospora subterranea and referred to 
Verticillium sp. and Stysanus sp. by Horne, of whose drawing this figure is a reproduc¬ 
tion. Note the similarity to those shown in figure F. 
